Preparation of chemically convertible tape

ABSTRACT

There is disclosed the in situ synthesizing of a polymeric material on a substrate by applying to the substrate a solid pyrolyzable binder which contains at least one member capable of polymerizing at or above the pyrolysis temperature of the binder and then applying heat so as to pyrolyze the binder and synthesize the polymer such that the pyrolyzed binder is not a part of the in situ synthesized polymeric material.

United States Patent Taylor Aug. 19, 1975 [54] PREPARATION OF CHEMICALLY3,379,561 4/1968 Manaka 1 17/122 7 CONVERTIBLE TAPE 3,419,412 12/1968Morris et al. 117/38 3,449,280 6/1969 Frigstad 260/292 [75] Inventor:Lynn J. Taylor, Haslett, MlCh. 3,666.615 5/1972 lwai et al. 161/185 [73]Assignee: Owens-Illinois, lnc., Toledo, Ohio [22] Filed; Mar, 8, 1973Primary ExaminerWilliam D, Martin App]. No.: 339,278

Related US. Application Data Division of Ser. No. 189,449, Oct. 14,1971, Pat. No. 3,816,162.

117/26 FA, 102 R, 119.6; 156/155; 26()/86.1 E, 89.5 A; 264/29 [56]References Cited UNITED STATES PATENTS 2,886,481) 5/1959 Deakin 156/55 XAssistant Examine1-Janyce A. Bell Attorney, Agent, or FirmDonald KeithWedding [57] ABSTRACT There is disclosed the in situ synthesizing of apolymeric material on a substrate by applying to the substrate a solidpyrolyzable binder which contains at least one member capable ofpolymerizing at or above the pyrolysis temperature of the binder andthen applying heat so as to pyrolyze the binder and synthesize thepolymer such that the pyrolyzed binder is not a part of the in situsynthesized polymeric material.

7 Claims, N0 Drawings PREPARATION OF CHEMICALLY CONVERTIBLE TAPE RELATEDAPPLICATION This is a division of copending US. patent application Ser.No. 189,449, filed Oct. 14, 1971 now US. Pat. No. 3,816,162.

BACKGROUND OF THE INVENTION This invention relates to the applying of apolymeric material to a substrate for purposes of a decorative orprotective coating, adhesion, etc.

The use of chemically reactive coating and adhesive compositions is wellknown in the prior art. Typically, a liquid coating compositioncontaining such materials is applied to a substrate, allowed to dry, andsubsequently heated to form a continuous coating by polymerization insitu.

The use of film-forming organic polymers in adhesive tapes is also wellknown. Typically, a tape based on an organic polymer, which mayoptionally contain modifying additives to make the surface tacky, isattached to one or more substrates with the aid of pressure. In thiscase, no chemical conversion takes place and the filmforming polymersimply remains an integral part of the coating or adhesive structure.

The use of chemically reactive organic materials in connection withcontinuous adhesive bonding tapes and films is also well known in theprior art. In particular, reference is made to epoxy resin, a phenolicresin also being present in the polyamide film or in the epoxy resin. Inboth cases the resulting films are intended to undergo chemicalconversion upon heating, but the film-forming (polyamide)resin remains apart of the cured composition and/or participates in the curingreaction.

In accordance with the practice of this invention, a polymeric materialis applied to a substrate by means of a binder substance which does notremain a part of the cured polymeric composition and/or participate inthe curing reaction.

More particularly, in accordance with the practice of this invention apolymeric material is applied to at least one substrate by means of apyrolyzable binder and an in situ polymer synthesis.

Still more particularly, there is provided a process of in situsynthesizing a polymeric material on at least one substrate whichcomprises applying to the substrate a solid pyrolyzable binder whichcontains at least one member capable of polymerizing at or above thepyrolysis temperature of the binder, and then applying heat so as topyrolyze the binder and synthesize the polymer such that the pyrolyzedbinder is not a part of the in situ synthesized polymeric material.

Thus in the present invention, a thermally removable polymer is used asa binder for one or more monomers or prepolymers. Since this binder isnot present in the final polymerized coating on the substrate, thecomposition of the final coating is determined entirely by the choice ofmonomeric or oligomeric reactants, and a wide variety of such reactantsmay be utilized.

In accordance with the practice of this invention, there is utilized abinder capable of pyrolyzing in any suitable environment, in thepresence or absence of an oxidizing agent. A

As used herein, pyrolyzing is defined as the decomposition of the binderto gaseous products without passing through a broad liquid range andwithout leaving a noticeable carbonaceous or other like residue whichwould interfere with the intended function of the in situ synthesizedpolymer.

The polymeric binder is one which will pyrolyze, as distinguished fromvaporization, when appropriate energy is applied thereto at somepredetermined energy level.

, Energy level, as used herein, is intended to include any reasonablymeasurable molecular energy state which is related to the pyrolyzing ofthe binder and also the synthesizing of the polymer. The most obviousenergy level is temperature, which has been defined as the averagemolecular kinetic energy. Hereinafter, temperature level will be used asa synonym for energy level. However, the invention is not limited totemperature level alone, but is intended to include any molecular energylevel or state which can be obtained by any appropriate energy from anysource or means, such as chemical, electrical, thermal, mechanical,sonic, etc. Likewise, the energy can be transmitted in any suitable formsuch as by electromagnetic radiation, visible or invisible, e.g.,infra-red, ultra-violet, X-rays, gamma rays, and beta rays.

The pyrolyzable binder, when solvent-free, is solid under the conditionsof handling, e.g., typically room or factory temperatures ranging fromabout 40F. to about F. However, more extreme temperatures arecontemplated if the conditions of handling so warrant.

The binder is typically selected from one or more pyrolyzable solidpolymers or copolymers such as high MW polyethers includingpolyoxymethylene, poly(tetrahydrofuran), poly( 1,3-dioxolane), andpoly(alkylene oxides), especially poly( ethylene oxide) orpoly(propylene oxide); poly(alkyl methacrylates) including those wherethe alkyl contains one to six carbons, especially poly(methylmethacrylate), poly(ethyl methacrylate), and poly(n-butyl methacrylate);methacrylate copolymers including methyl methacrylate/n-butylmethacrylate copolymers, methyl methacrylate/alpha-methyl styrenecopolymers, n-butyl methacrylate/alpha-methyl styrene copolymers, methylmethacrylate/styrene copolymers, methyl methacrylate/dimethyl itaconatecopolymers; and other selected polymers and copolymers includingpolyisobutylene; poly(trimethylene carbonate); poly(beta-propiolactone); poly(deltavalerolactone); poly(ethylene carbonate);poly(propylene carbonate); poly( ethylene oxalate); vinyltoluene/alpha-methylstyrene copolymers; styrene/alpha-methylstyrenecopolymers; cellulose ethers, and olefin-sulfur dioxide copolymers.

In one specific embodiment hereof, there is used a polymeric bindermaterial having oxygen atoms selectively incorporated in its molecularchain, as, for example, peroxy linkages in the chain. Such a pyrolyzablepolymer is disclosed in copending US. Patent application Ser. No.653,020, filed July 13, 1967 by Dr. Don N. Gray and assigned to the sameassignee as that of the instant patent application. Typically there isused a copolymer, terpolymer, or quadpolymer of oxygen and at least onemonomer of alkyl methacrylate with the alkyl containing one to sixcarbon atoms, e.g., methyl to hexyl, preferably butyl. Copolymers ofoxygen with other vinyl monomers may also be utilized.

The common characteristic of the selected polymeric binder material isthat it must be solid at ambient temperature and pyrolyzable at anelevated temperature, e.g., about 250C. to about 450C.

This pyrolysis mechanism of removal of the composition of the inventionis of great advantage in non-oxygen-containing atmospheres, but thecompositions may also be used in an oxygen-containing atmosphere. Thischaracteristic permits the use of a continuum of atmospheric pressuresdownward from somewhat less than 14.7 lbs. per sq. in. absolute to vacuaapproaching the micron range. Likewise, inert environments such asnitrogen, argon, etc. may be used.

Examples of suitable polymerizable members include:

difunctional, trifunctional and polyfunctional organic amines, includingp-phenylenediamine, mphenylenediamine, benzidine,4,4-methylenedianiline,

4,4-oxydianiline, 4,4-thiodianiline, 3,3 ',4,4'- tetraaminobiphenyl,4,4'-methylenebis( ochloroaniline hexamethylenediamine, ethylenediamine,l,2-diaminopropane, 1,3-diaminopropane, 1,4- diaminoanthraquinone,2,6-diaminoanthraquinone, melamine, 1,4-cyclohexanediamine, 4,4-diaminostilbene, and 4,4-diaminodiphenyl sulfone;

difunctional, trifunctional, and polyfunctional organic carboxylicacids, including adipic acid, sebacic acid, azelaic acid, dimer acid,phthalic acid, isophthalic acid, biphenyldicarboxylic acid (variousisomers), trimellitic acid, pyromellitic acid, trimer acid,benzophenone-3,3',4,4-tetracarboxylic acid, l,8,4,5-naphthalenetetracarboxylic acid, and 2,3,6,7-anthraquinonetetracarboxylic acid;

organic anhydrides including phthalic anhydride, maleic anhydride,succinic anhydride, pyromellitic dianhydride, benzophenone 3,3,4,4'tetracarboxylic acid dianhydride, l,8,4,5-naphthalene tetracarboxylicacid dianhydride, and 2,3,6,7-anthraquinonetetracarboxylic aciddianhydride;

difunctional, trifunctional, and polyfunctional esters, includingdimethyl azelate, dimethyl sebacate, diethyl adipate, dimethylterephthalate, diphenyl terephthalate, diphenyl isophthalate, andbis(2-hydroxyethyl) terephthalate;

difunctional, trifunctional, and polyfunctional organic isocyanatesincluding hexamethylene diisocyanate, toluene diisocyanate (variousisomers), xylene diisocyanate (various isomers), diphenylmethane-4,4'-diisocyanate, and suitably blocked derivatives of the above;

difunctional, trifunctional, and polyfunctional alcohols and phenols,including 1,4-cyclohexanediol, pxylene-a,a-diol, hydroquinone, catechol,resorcinol, 2,2-bis(p-hydroxyphenyl) propane, p,p'-biphenol, 1, l l-trimethylolpropane, and pentaerythritol;

difunctional, trifunctional, and polyfunctional organic acyl halides,including adipyl chloride, sebacyl chloride, azelaoyl chloride, andterephthaloyl chloride; difunctional, trifunctional, and polyfunctionalhydrazides, including adipic acid dihydrazide, azelaic acid dihydrazide,sebacic acid dihydrazide, and terephthalic acid dihydrazide;

And other materials such as diphenyl carbonate and terephthalaldehyde.

Examples of polymerizable members also include prepolymers:

Epoxy Resins; Urea-Formaldehyde Resins; Phenol- Formaldehyde Resins;Malamine-Formaldehyde Resins; Furan Resins; Polyanhydrides;Polyhydrazides; low molecular weight polyethers; low molecular weightpolyesters; and Silicone Resins.

In addition to the monomer and/or prepolymer, the pyrolyzable binder maybe loaded with other suitable ingredients providing such do notinterfere with the pyrolysis and/0r polymerization process.

Suitable ingredients contemplated include fillers, pigments, reinforcingagents, colorants, stabilizers, glass fibers, carbon black,plasticizers, catalysts, initiators,

In one preferred embodiment hereof, the solid pyrolyzable binder andpolymer forming material (monomer or prepolymer), including anyadditionally loaded ingredients, are prepared in the form of achemically convertible tape.

In the practice of such embodiment, it is contemplated that thechemically convertible tape will ordinarily be prepared by casting froma solution containing the thermally removable binder, one or morevolatile solvents for that binder, and the monomer(s) or prepolymer(s),which may or may not be soluble in the solvent or solvent mixture.

A mixture of a pyrolyzable polymeric binder, a solvent for the binderand a polymerizable organic member is applied to a surface and themixture dried at a temperature between about 0 and about 200C.

Other methods of preparing the chemically convertible tape are alsocontemplated. These include tape formation by extrusion, or calenderingof suitable compositions containing molten polymeric binder, as well ascasting from a suitable dispersion or emulsion in aqueous media.Fabrication of the tape by impregnation or coating of a previouslyprepared film of pyrolyzable binder is also contemplated.

In the application of this invention, a surface to be coated is coveredwith a film or tape which contains a material or combination ofmaterials which can be coverted by heating into a suitable coating oradhesive material. Subsequent heating leads to the initiation ofchemical reactions leading to the formation of a coating (or interlayer)of a suitable (polymeric) material.

Such a tape or film would typically consist of at least two components:a film-forming binder of high molecular weight and one or more reactivecomponents, which would ordinarily be materials of low molecular weight.

Depending upon the choice of reactive components, various types ofpolymeric materials can be prepared in situ according to this invention.Specific embodiments would involve the use of the following types ofreactive components.

1. An epoxy resin and a curing agent such as an amine or anhydride;

2. A diamine and a dianhydride, which upon heating will react to form apolyimide;

3. Two materials capable of reacting to form a polyurethane, such as ablocked isocyanate and a polyether or polyester;

4. A phenolic resin, with or without added curing catalysts;

5. A melamine-formaldehyde or urea-formaldehyde resin, with or withoutadding curing catalysts.

It is envisioned that, in most cases, the reactive components will beintimately mixed with the binder e.g.,

by dispersing or dissolving the reactive components in a solution of thebinder, then casting a film from the resulting mixture). However, itwould also be possible to apply a reactive component as a coating on thesurface of a film of binder, or to sandwich reactive components betweentwo layers of binder. In certain cases involving two or more reactivecomponents, it may be necessary or desirable to have each of thereactive components present in a separate layer of a tape con sisting oftwo or more layers.

As already noted, fillers, reinforcing agents, colorants, and otheradditives (e.g., glass fibers, carbon black, pigments, stabilizers,etc.) may also be incorporated in the tape; these will be present assuch in the final coating provided they are not destroyed by heating orby interaction with other materials present.

In comparison to the conventional methods of applying chemicallyconvertible coating materials as liquid paints, the following advantagesare anticipated by the practice of this invention:

1. Increased convenience of handling and application to surfaces;

2. Storage stability over prolonged periods, without the need forstorage in closed containers;

3. In some instances, the need for running pre-polymerizations(B-staging) can be eliminated;

4. Disadvantages inherent in the use of solvent-based coatings (solventcost, fire and health hazards, air-pollution, etc.) can be avoided; and

5. Mixing of reactive components just prior to the coating process isavoided.

The following EXAMPLES represent some of the best embodimentscontemplated by the inventor in the practice of this invention.

EXAMPLE I A mixture of 3 grams (g.) olefin-sulfur dioxide copolymer(OX-3618, Dow Chemical Co.), g. xylene, 15 g. n-butanol, and 3 g.commercially available urea-formaldehyde resin solution (BeckamineP-l38- 60, Reichhold Chemical Co., 60% resin solids in xylene/butanol)is prepared and agitated until homogeneous.

A tape is prepared from a portion of the resulting solution, by castingonto a polytetrafluoroethylene substrate. After evaporation ofvolatiles, a piece of the resulting tape is placed on a glass substrateand heated 3 hours in air at ca. 300 350F. An adherent, continuous,yellowish coating is formed. An acetone-wipe test indicates that thecuring of the coating is substantially complete.

The Dow Chemical Company QX-36l8 in an alpha-olefin/sulfone copolymerhaving a softening temperature of 50C. to 60C., a polymer melttemperature of 135C. to 145C, and a decomposition initiation temperatureof about 175C. It is soluble in ketones and chlorinated solvents such asmethylene chloride and ethylene chloride. After five minutes at 240C.,about 99.3 percent is converted to volatile products. It

exhibits a strong IR bond at 720/cm, lllO/cm, and

l300/cm.

EXAMPLE 2 To a solution of 20 grams g.) polyisobutylene in 180milliliters (ml.) benzene, there is added 10.9 g. pyromelliticdianhydride, 9.9 g. 4,4'-methylene-dianiline, and about 10 g.chlorinated biphenyl plasticizer (Monsanto Aroclor 1242). The resultingmixture is agitated until substantially homogeneous. A portion of theresulting mixture is cast onto a polytetrafluoroethylene substrate, andallowed to dry. A portion of the resulting tape is placed on a glasssubstrate and heated 2 hours at about 400F., then 6 hours at about 700F.A brown polymeric coating, substantially insoluble inN,N-dimethylformamide, is formed.

I claim:

1. A process for preparing a tape which comprises preparing a mixture ofa pyrolyzable polymeric binder, a solvent for said binder and apolymerizable organic member, said pyrolyzable polymeric binder beingsolid at a temperature of about 40F. to about F. and said polymerizableorganic member being polymerizable at or above the pyrolyzingtemperature of the binder;

applying said mixture to a surface;

and drying said mixture at a temperature between about 0C. and 200C.

2. The process of claim 1, wherein the pyrolyzable binder is selectedfrom polyethers, poly( alkyl methacrylates), methacrylate copolymers,polyisobutylene, poly(trimethylene carbonate), poly(betapropiolactone),poly(delta-valerolactone), poly(ethylene carbonate), poly(propylenecarbonate), poly- (ethylene oxalate), vinyl toluene/alpha-methyl styrenecopolymers, styrene/alpha-methyl styrene copolymers, cellulose ethers,and olefinsulfur dioxide copolymers.

3. The process of claim 1, wherein the polymerizable organic membercomprises at least one compound selected from difunctional,trifunctional, and polyfunctional organic amines, carboxylic acids,esters, isocyanates, alcohols, phenols, acyl halides, and hydrazides.

4. The process of claim 1, wherein the polymerizable organic membercomprises at least one substance selected from epoxy resins,urea-formaldehyde resins, phenol-formaldehyde resins,melamine-formaldehyde resins, furan resins, polyanhydrides,polyhydrazides, polyethers, polyesters, and silicone resins.

5. The process of claim 1 wherein the polymerizable organic membercontains at least one organic anhydride or dianhydride.

6. The process of claim 1, wherein the polymerizable organic member is amixture of an organic diamine and an organic dianhydride.

7. The process of claim 1, wherein the polymerizable organic member is amixture of a tetrafunctional organic amine and an organic diester.

1. A PROCESS FOR PREPARING A TAPE WHICH COMPRISES PREPARING A MIXTURE OF A PYROLYZABLE POLYMERRIC BINDER, A SOLVENT FOR SAID BINDER AND A POLYMERIZABLE ORGANIC MEMBER, SAID PYROLYZABLE POLYMERIC BINDER BEING SOLID AT A TEMPERATURE OF ABOUT 40*F. TO ABOUT 120*F. AND SAID POLYMERIZABLE ORGANIC MEMBER BEING POLYMERIZABLE AT OR ABOVE THE PYROLYZING TEMPERATURE OF THE BINDER, APPLYING SAID MIXTURE TO A SURFACE, AND DRYING SAID MIXTURE AT A TEMPERATURE BETWEEN ABOUT 0*C. AND 200*C.
 2. The process of claim 1, wherein the pyrolyzable binder is selected from polyethers, poly(alkyl methacrylates), methacrylate copolymers, polyisobutylene, poly(trimethylene carbonate), poly(beta-propiolactone), poly(delta-valerolactone), poly(ethylene carbonate), poly(propylene carbonate), poly(ethylene oxalate), vinyl toluene/alpha-methyl styrene copolymers, styrene/alpha-methyl styrene copolymers, cellulose ethers, and olefinsulfur dioxide copolymers.
 3. The process of claim 1, wherein the polymerizable organic member comprises at least one compound selected from difunctional, trifunctional, and polyfunctional organic amines, carboxylic acids, esters, isocyanates, alcohols, phenols, acyl halides, and hydrazides.
 4. The process of claim 1, wherein the polymerizable organic member comprises at least one substance selected from epoxy resins, urea-formaldehyde resins, phenol-formaldehyde resins, melamine-formaldehyde resins, furan resins, polyanhydrides, polyhydrazides, polyethers, polyesters, and silicone resins.
 5. The process of claim 1 wherein the polymerizable organic member contains at least one organic anhydride or dianhydride.
 6. The process of claim 1, wherein the polymerizable organic member is a mixture of an organic diamine and an organic dianhydride.
 7. The process of claim 1, wherein the polymerizable organic member is a mixture of A tetrafunctional organic amine and an organic diester. 